Method and catalyst system for producing aromatic carbonates

ABSTRACT

A method and catalyst system for producing aromatic carbonates from aromatic hydroxy compounds. In one embodiment, the method includes the step of contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system having an effective amount of an iron source in the absence of a Group VIII B metal source. In various alternative embodiments, the carbonylation catalyst system can include at least one inorganic co-catalyst, as well as a halide composition and/or a base.

BACKGROUND

[0001] 1. Field of the Invention

[0002] The present invention is directed to a method and catalyst systemfor producing aromatic carbonates and, more specifically, to a methodand catalyst system for producing diaryl carbonates through thecarbonylation of aromatic hydroxy compounds.

[0003] 2. Discussion of Related Art

[0004] Aromatic carbonates find utility, inter alia, as intermediates inthe preparation of polycarbonates. For example, a popular method ofpolycarbonate preparation is the melt transesterification of aromaticcarbonates with bisphenols. This method has been shown to beenvironmentally superior to previously used methods which employedphosgene, a toxic gas, as a reagent and chlorinated aliphatichydrocarbons, such as methylene chloride, as solvents.

[0005] Various methods for preparing aromatic carbonates have beenpreviously described in the literature and/or utilized by industry. Amethod that has enjoyed substantial popularity in the literatureinvolves the direct carbonylation of aromatic hydroxy compounds withcarbon monoxide and oxygen. In general, practitioners have found thatthe carbonylation reaction requires a rather complex catalyst system.For example, in U.S. Pat. No. 4,187,242, which is assigned to theassignee of the present invention, Chalk reports that a carbonylationcatalyst system should contain a Group VIII B metal, such as ruthenium,rhodium, palladium, osmium, iridium, platinum, or a complex thereof.Further refinements to the carbonylation reaction include theidentification of organic co-catalysts, such as terpyridines,phenanthrolines, quinolines and isoquinolines in U.S. Pat. No. 5,284,964and the use of certain halide compounds, such as quaternary ammonium orphosphonium halides in U.S. Pat. No. 5,399,734, both patents also beingassigned to the assignee of the present invention.

[0006] Unfortunately, due to the significant expense of using a GroupVIII B metal as the primary catalyst in a bulk process, the economics ofthe aforementioned carbonylation systems is strongly dependent on thenumber of moles of aromatic carbonate produced per mole of Group VIII Bmetal utilized (i.e. “catalyst turnover”). Consequently, much work hasbeen directed to the identification of efficacious co-catalystcombinations that increase primary catalyst turnover. For example, inU.S. Pat. No. 5,231,210, which is also assigned to the present assignee,Joyce et al. report the use of a cobalt pentadentate complex as aninorganic co-catalyst (“IOCC”). In U.S. Pat. No. 5,498,789, Takagi etal. report the use of lead as an IOCC. In U.S. Pat. No. 5,543,547, Iwaneet al. report the use of trivalent cerium as an IOCC. In U.S. Pat. No.5,726,340, Takagi et al. report the use of lead and cobalt as a binaryIOCC system.

[0007] Until the work underlying the teachings of the presentdisclosure, however, few or no resources have been dedicated toidentifying effective substitutes for the Group VIII B metal (typicallypalladium) as the primary catalyst in the carbonylation reaction. Giventhe recent, substantial increases in the cost of palladium, evensubstitutes exhibiting comparatively low activity can be economicallyviable.

[0008] Unfortunately, the literature is not instructive regarding therole of many catalyst components in the carbonylation reaction (i.e. thereaction mechanism), and meaningful guidance regarding theidentification of effective combinations of catalyst system componentsis cursory at best. Accordingly, due to the lack of guidance in theliterature, the identification of effective carbonylation catalystsystems has become a serendipitous exercise.

[0009] As the demand for high performance plastics has continued togrow, new and improved methods of providing product more economicallyare needed to supply the market. In this context, various processes andcatalyst systems are constantly being evaluated; however, the identitiesof additional economically effective catalyst systems for theseprocesses continue to elude the industry. Consequently, a long felt, yetunsatisfied need exists for economically superior methods and catalystsystems for producing aromatic carbonates and the like.

SUMMARY OF THE INVENTION

[0010] Accordingly, the present invention is directed to a method andcatalyst system for producing aromatic carbonates. In one embodiment,the method includes the step of contacting at least one aromatic hydroxycompound with oxygen and carbon monoxide in the presence of acarbonylation catalyst system having an effective amount of an ironsource in the absence of an effective amount of a Group VIII B metalsource.

[0011] In various alternative embodiments, the carbonylation catalystsystem can include catalytic amounts of at least one inorganicco-catalyst, as well as effective amounts of a halide composition and/ora base.

BRIEF DESCRIPTION OF THE DRAWING

[0012] Various features, aspects, and advantages of the presentinvention will become more apparent with reference to the followingdescription, appended claims, and accompanying drawing, wherein theFIGURE is a schematic view of a device capable of performing an aspectof an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0013] The present invention is directed to a method and catalyst systemfor producing aromatic carbonates. In one embodiment, the methodincludes the step of contacting at least one aromatic hydroxy compoundwith oxygen and carbon monoxide in the presence of a carbonylationcatalyst system having an effective amount of an iron source in theabsence of an effective amount of a Group VIII B metal source.

[0014] For convenience, the constituents of the catalyst systemdescribed herein arc called “components” irrespective of whether areaction between specific components actually occurs either before orduring the carbonylation reaction. Therefore, the catalyst system mayinclude the components and any reaction products thereof.

[0015] Unless otherwise noted, the term “effective amount” as usedherein includes that amount of a component capable of either increasing(directly or indirectly) the yield of the carbonylation product orincreasing selectivity toward an aromatic carbonate. Optimum amounts ofa given component can vary based on reaction conditions and the identityof other components, yet can be readily determined in light of thediscrete circumstances of a given application.

[0016] Aromatic hydroxy compounds which may be used in the presentprocess include aromatic mono or polyhydroxy compounds, such as phenol,cresol, xylenol, resorcinol, hydroquinone, and bisphenol A. Aromaticorganic mono hydroxy compounds are preferred, with phenol being morepreferred.

[0017] The carbonylation catalyst system contains an effective amount ofan iron source as the primary catalyst component. Suitable iron sourcesinclude iron halides, nitrates, carboxylates, oxides and iron complexescontaining carbon monoxide, amines, phosphines or olefins. As usedherein, the term “complex” includes coordination or complex compoundscontaining a central ion or atom. The complexes may be nonionic,cationic, or anionic, depending on the charges carried by the centralatom and the coordinated groups. Other common names for these complexesinclude complex ions (if electrically charged), Werner complexes, andcoordination complexes. In various applications, it may be preferable toutilize iron salts of organic acids, including carboxylates with C₂₋₆aliphatic acids. Suitable iron sources include iron (II or III)acetylacetonate and iron (II or III) acetate, as well as iron (III)bromide anhydrous, iron (II or III) nitrate, ferrocene, acetylferrocene,tris(2,2,6,6-tetramethyl-3,5-heptanedionate) iron (III), and iron (II)methylcyclopentadienyl.

[0018] The iron source may be a non-supported iron salt or complex. Asused herein, the term “non-supported” indicates the absence ofindustrially conventional catalyst supports based on carbon, elementoxides, element carbides or element salts in various presentations.Examples of supports containing carbon are coke, graphite, carbon blackand activated carbon. Examples of element oxide catalyst supports areSiO₂ (natural or synthetic silicas, quartz), Al₂O₃ (α-, γ-Al₂O₃),aluminas, natural and synthetic aluminosilicates (zeolites), TiO₂(rutile, anatase), ZrO₂ and ZnO. Examples of element carbides and saltsare SiC, AlPO₄, BaSO₄, and CaCO₃.

[0019] The present iron based catalyst system does not require acomponent chosen from the Group VIII B metals (i.e., Ru, Pt, Pd, Rh, Os,Ir) or a compound thereof. Surprisingly, the presently disclosedcatalyst system effectively catalyzes the carbonylation reaction in theabsence of a costly Group VIII B metal source, thereby effectivelyinsulating the process from the volatile market for these elements.

[0020] In various alternative embodiments, the carbonylation catalystsystem can include a catalytic amount of at least one inorganicco-catalyst (IOCC). It has been discovered that IOCC's and combinationsof IOCC's can effectively catalyze the carbonylation reaction in thepresence of the aforementioned iron-based catalyst system. Such IOCC'sand combinations include copper, lead, copper and zirconium, titaniumand cerium, lead and titanium, lead and zirconium, copper and titanium,copper and lead, and titanium and zirconium. Additional IOCC's may beused in the carbonylation catalyst system, provided the additional IOCCdoes not deactivate (i.e. “poison”) the original IOCC combination.

[0021] An IOCC can be introduced to the carbonylation reaction invarious forms, including salts and complexes, such as tetradentate,pentadentate, hexadentate, or octadentate complexes. Illustrative formsmay include oxides, halides, carboxylates, diketones (includingbeta-diketones), nitrates, complexes containing carbon monoxide orolefins, and the like. Suitable beta-diketones include those known inthe art as ligands for the IOCC metals of the present system. Examplesinclude, but are not limited to, acetylacetone, benzoylacetone,dibenzoylmethane, diisobutyrylmethane, 2,2-dimethylheptane-3,5-dione,2,2,6-trimethylheptane-3,5-dione, dipivaloylmetharie, andtetramethylheptanedione. The quantity of ligand is preferably not suchthat it interferes with the carbonylation reaction itself, with theisolation or purification of the product mixture, or with the recoveryand reuse of catalyst components. An IOCC may be used in its elementalform if sufficient reactive surface area can be provided. It may bepreferable that an IOCC is non-supported as discussed above relative tothe iron source.

[0022] IOCC's are included in the carbonylation catalyst system incatalytic amounts. In this context a “catalytic amount” is an amount ofIOCC (or combination of IOCC's) that increases the number of moles ofaromatic carbonate produced per mole of iron utilized; increases thenumber of moles of aromatic carbonate produced per mole of halidecomposition utilized; or increases selectivity toward aromatic carbonateproduction beyond that obtained in the absence of the IOCC (orcombination of IOCC's). Optimum amounts of an IOCC in a givenapplication will depend on various factors, such as the identity ofreactants and reaction conditions. For example, when copper is utilizedas an IOCC in the reaction, the molar ratio of copper relative to ironat the initiation of the reaction is preferably between about 1 andabout 100.

[0023] The carbonylation catalyst system may further contain aneffective amount of a halide composition, such as an organic halidesalt. In various preferred embodiments, the halide composition can be anorganic bromide or chloride salt. The salt may be a quaternary ammoniumor phosphonium salt, such as tetraethylammonium bromide,tetraethylammonium chloride, tetrabutylammonium chloride, or the like.To address economic or regulatory concerns, alkali metal or alkalineearth metal salts may be preferable in certain applications. Inpreferred embodiments, the carbonylation catalyst system can containbetween about 5 and about 2000 moles of halide per mole of ironemployed, and, more preferably, between about 50 and about 1000 molarequivalents of halide are used.

[0024] The carbonylation catalyst system can also include an effectiveamount of a base. Any desired bases or mixtures thereof, whether organicor inorganic may be used. A non-exclusive listing of suitable inorganicbases include alkali metal hydroxides and carbonates; C₂-C₁₂carboxylates or other salts of weak acids; and various alkali metalsalts of aromatic hydroxy compounds, such as alkali metal phenolates.Hydrates of alkali metal phenolates may also be used. Examples ofsuitable organic bases include tertiary amines and the like. Preferably,the base used is an alkali metal salt incorporating an aromatic hydroxycompound, more preferably an alkali metal salt incorporating thearomatic hydroxy compound to be carbonylated to produce the aromaticcarbonate. Suitable bases include sodium phenoxide and sodium hydroxide.In preferred embodiments, between about 5 and about 1000 molarequivalents of base are employed (relative to iron), and, morepreferably, between about 50 and about 700 molar equivalents of base areused.

[0025] The carbonylation reaction can be carried out in a batch reactoror a continuous reactor system. Due in part to the low solubility ofcarbon monoxide in organic hydroxy compounds, such as phenol, it ispreferable that the reactor vessel be pressurized. In preferredembodiments, gas can be supplied to the reactor vessel in proportions ofbetween about 2 and about 50 mole percent oxygen, with the balance beingcarbon monoxide or a combination of at least one inert gas and carbonmonoxide and, in any event, outside the explosion range for safetyreasons. It is contemplated that oxygen can be supplied in diatomic formor from another oxygen containing source, such as peroxides and thelike. Additional gases may be present in amounts that do notdeleteriously affect the carbonylation reaction. The gases may beintroduced separately or as a mixture. A total pressure in the range ofbetween about 10 and about 250 atmospheres is preferred. Drying agents,typically molecular sieves, may be present in the reaction vessel.Reaction temperatures in the range of between about 60° C. and about150° C. are preferred. Gas sparging or mixing can be used to aid thereaction.

[0026] In order that those skilled in the art will be better able topractice the present invention reference is made to the FIGURE, whichshows an example of a continuous reactor system for producing aromaticcarbonates. The symbol “V” indicates a valve and the symbol “P”indicates a pressure gauge.

[0027] The system includes a carbon monoxide gas inlet 10, an oxygeninlet 11, a manifold vent 12, and an inlet 13 for a gas, such as carbondioxide. A reaction mixture can be fed into a low pressure reservoir 20,or a high pressure reservoir 21, which can be operated at a higherpressure than the reactor for the duration of the reaction. The systemfurther includes a reservoir outlet 22 and a reservoir inlet 23. The gasfeed pressure can be adjusted to a value greater than the desiredreactor pressure with a pressure regulator 30. The gas can be purifiedin a scrubber 31 and then fed into a mass flow controller 32 to regulateflow rates. The reactor feed gas can be heated in a heat exchanger 33having appropriate conduit prior to being introduced to a reactionvessel 40. The reaction vessel pressure can be controlled by a backpressure regulator 41. After passing through a condenser 25, the reactorgas effluent may be either sampled for further analysis at valve 42 orvented to the atmosphere at valve 50. The reactor liquid can be sampledat valve 43. An additional valve 44 can provide further system control,but is typically closed during the gas flow reaction.

[0028] In the practice of one embodiment of the invention, thecarbonylation catalyst system and aromatic hydroxy compound are chargedto the reactor system. The system is sealed. Carbon monoxide and oxygenare introduced into an appropriate reservoir until a preferred pressure(as previously defined) is achieved. Circulation of condenser water isinitiated, and the temperature of the heat exchanger 33 (e.g., oil bath)can be raised to a desired operating temperature. A conduit 46 betweenheat exchanger 33 and reaction vessel 40 can be heated to maintain thedesired operating temperature. The pressure in reaction vessel 40 can becontrolled by the combination of reducing pressure regulator 30 and backpressure regulator 41. Upon reaching the desired reactor temperature,aliquots can be taken to monitor the reaction.

EXAMPLES

[0029] The following examples are included to provide additionalguidance to those skilled in the art in practicing the claimedinvention. The examples provided are merely representative of the workthat contributes to the teaching of the present application.Accordingly, these examples are not intended to limit the invention, asdefined in the appended claims, in any manner. Unless otherwisespecified, all parts are by weight, and all equivalents are relative toiron. Reaction products were verified by gas chromatography. Unlessotherwise noted, all reactions were carried out in a glass, batchreactor at 100° C. in an approximately 6-9% O₂ in CO atmosphere. Theglass reactor was sealed with a semi-permeable membrane and placed in anautoclave containing the reaction atmosphere at a pressure ofapproximately 110 atmosphere (i.e., negligible pressure differentialacross the walls of the glass reaction vessel). Reaction time was 3hours for each run.

[0030] In the following examples, the aromatic carbonate produced isdiphenylcarbonate (DPC). For convenience, the number of moles of DPCproduced per mole of iron utilized is referred to as the iron turnovernumber (Fe TON).

Example 1

[0031] Diphenyl carbonate was produced by adding, at ambient conditions,a substantially homogeneous catalyst system containing iron in the formof either iron (III) acetylacetonate (“Fe(acac)₃”) or iron (III) nitrate(“Fe(NO₃)₃”) 5 equivalents of titanium in the form of titanium (IV)oxide acetylacetonate (“TiO(acac)₂”), 2 equivalents of cerium in theform of cerium (III) acetylacetonate (“Ce(acac)₃”), differing amounts ofhalide compositions in the form of either tetraethylammonium bromide(“TEAB”) or tetraethylammonium chloride (“TEAC”), and 50 equivalents ofNaOH to a glass reaction vessel containing phenol. The components wereheated to 100° C. for 3 hours in a reaction atmosphere comprised of 3%oxygen, 6% nitrogen, and 91% carbon monoxide. Total pressure in thereaction zone was approximately 102 atm. The following results wereobserved: Experiment Fe source Halide Halide No. 1 mM source EquivalentsFe TON 1 Fe(acac)₃ TEAC 200 2 2 Fe(NO₃)₃ TEAB  50 3

[0032] The data show that a Fe TON at least as high as 3 can be obtainedutilizing an embodiment of the present catalyst system. Based on theresults of these experiments, it is evident that a catalyst systemcontaining Fe, Ce, Ti, an onium halide, and a base can effectivelycatalyze the carbonylation reaction.

Example 2

[0033] The general procedure of Example 1 was repeated with various ironsources, such as Fe(acac)₃, iron (II) acetate (“Fe(OAc)₂”), iron (III)bromide (“FeBr₃”), and iron (II) methylcyclopentadienyl (“Fe(Cp)₂”).Various inorganic co-catalyst combinations were employed in the presenceof 50 equivalents of various halide compositions, including TEAB andtetrabutylammonium chloride (“TBAC”). Some experimental runs werecarried out in the presence of a base. All reactions were carried out ina 7.4% oxygen in carbon monoxide atmosphere at a total pressure ofapproximately 109 atm. to produce the following results: Fe Experimentsource IOCC IOCC #1 IOCC IOCC #2 NaOH Halide Fe No. 1 mM #1 Equiv. #2Equiv. Equiv. source TON 1 Fe(acac)₃ Pb 5 Ti 1 50 TEAB 3 2 Fe(acac)₃ Pb5 Ti 1 50 TEAB 2 3 Fe(acac)₃ Pb 5 Zr 5 50 TBAC 3 4 Fe(acac)₃ Cu 1 Ti 550 TEAB 3 5 Fe(acac)₃ Cu 5 Zr 5 50 TEAB 2 6 Fe(OAc)₂ Pb 1 Cu 5 — TEAB 57 Fe(OAc)₂ Pb 5 Ti 5 50 TEAB 5 8 Fe(OAc)₂ Cu 1 Ti 5 50 TEAB 3 9 Fe(OAc)₂Cu 5 Zr 1 — TEAB 2 10 Fe(OAc)₂ Ti 5 Zr 5 50 TBAC 2 11 Fe(Cp)₂ Pb 5 Cu 550 TEAB 3 12 Fe(Cp)₂ Pb 5 Cu 5 50 TEAB 2 13 Fe(Cp)₂ Pb 1 Ti 1 50 TEAB 614 Fe(Cp)₂ Pb 1 Ti 1 50 TEAB 2 15 Fe(Cp)₂ Cu 5 Ti 1 50 TBAC 3 16 Fe(Cp)₂Cu 5 Ti 5 50 TEAB 3 17 Fe(Cp)₂ Cu 5 Ti 5 50 TEAB 2 18 Fe(Cp)₂ Cu 5 Zr 150 TBAC 2 19 Fe(Cp)₂ Cu 5 Zr 1 50 TBAC 4 20 Fe(Cp)₂ Ti 1 Zr 1 50 TEAB 421 Fe(Cp)₂ Ti 1 Zr 1 50 TEAB 2 22 FeBr₃ Pb 1 Cu 5 50 TBAC 3 23 FeBr₃ Pb1 Ti 5 50 TEAB 3 24 FeBr₃ Pb 5 Zr 1 50 TBAC 3 25 FeBr₃ Pb 5 Zr 1 50 TBAC3 26 FeBr₃ Cu 5 Ti 5 50 TEAB 3 27 FeBr₃ Ti 5 Zr 1 50 TEAB 6 28 FeBr₃ Ti5 Zr 5 50 TEAB 2

[0034] The results show that various combinations of Fe, IOCC, oniumhalide, and base can effectively catalyze the carbonylation reaction.

Example 3

[0035] The general procedure of Examples 1 and 2 was repeated with 1 mMof various iron sources, 100 equivalents of TEAB, and various amounts ofeither lead or copper, Lead was provided as lead (II) oxide (“PbO”) andcopper as copper (II) acetylacetonate (“Cu(acac)₂”). Iron sources usedfor these experimental runs include Fe(acac)₃, Fe(OAc)₂, FeBr₃,ferrocene (“Fe(C₅H₅)₂”), and iron (II) nitrate (“Fe(NO₃)₂”). Reactionswere carried out in a 7.8% oxygen in carbon monoxide atmosphere atapproximately 110 atm. total pressure. The following results wereobserved: Experiment Fe source Cu(acac)₂ PbO TEAB Fe No. 1 mMEquivalents Equivalents Equiv. TON 1 Fe(acac)₃ 5 — 100 4 2 Fe(OAc)₂ 5 —100 3 3 Fe(OAc)₂ 5 — 100 6 4 FeBr₃ 5 — 100 3 5 FeBr₃ 5 — 100 5 6Fe(C₅H₅)₂ 5 — 100 6 7 Fe(acac)₃ — 10 100 3 8 Fe(OAc)₂ — 10 100 5 9 FeBr₃— 10 100 4 10 FeBr₃ — 10 100 11 11 Fe(C₅H₅)₂ — 10 100 4 12 Fe(C₅H₅)₂ —10 100 3 13 Fe(NO₃)₂ — 10 100 11 14 Fe(NO₃)₂ — — — 16

[0036] The results show that various combinations of Fe alone, as wellas in combination with an IOCC and onium bromide can effectivelycatalyze the carbonylation reaction.

Example 4

[0037] The general procedure of Examples 1-3 was repeated with 1 mM ofvarious iron sources, 100 equivalents of either TEAB or TBAC, andvarious amounts of either PbO or Cu(acac)₂. Reactions were carried outin a 7.8% oxygen in carbon monoxide atmosphere at approximately 56 atm.total pressure. The following results were Experiment Fe sourceCu(acac)₂ PbO Halide Fe No. 1 mM Equivalents Equivalents 100 eq. TON 1Fe(acac)₃ — 10 TEAB 2 2 Fe(OAc)₂ — 10 TEAB 4 3 Fe(acac)₃ 5 — TBAC 4 4FeBr₃ 5 — TBAC 4 5 Fe(NO₃)₂ 5 — TBAC 3 6 Fe(NO₃)₂ 5 — TBAC 3

[0038] The results show that various combinations of Fe, IOCC, and oniumhalide can effecitively catalyze the carbonylation reaction at lowerpressures.

Example 5

[0039] The general procedure of Examples 1-4 was repeated with variousiron sources, various inorganic co-catalyst combinations, and 100equivalents of either TEAC or TEAB. IOCC sources included TiO(acac)₂,PbO, Zr(OBu)₄, and Cu(acac)₂. Some experimental runs were carried out inthe presence of a base. All reactions were carried out in a 9% oxygen incarbon monoxide atmosphere at a total pressure of approximately 102 atm.to produce the following results: Fe Experiment source IOCC IOCC #1 IOCCIOCC #2 NaOH Halide Fe No. 1 mM #1 Equiv. #2 Equiv. Equiv. source TON 1FeBr₃ Ti 2 Pb 2 50 TEAC 2 2 FeBr₃ Ti 2 Pb 2 50 TEAC 2 3 Fe(Cp)₂ Zr 5 Pb2 — TBAB 2 4 Fe(Cp)₂ Zr 5 Pb 2 — TEAB 2 5 Fe(Cp)₂ Cu 5 Ti 5 — TEAB 2 6Fe(OAc)₃ Pb 2 Cu 5 50 TEAB 3 7 Fe(OAc)₃ Pb 2 Cu 5 50 TEAB 2 8 Fe(acac)₃Cu 5 Ti 2 50 TEAB 1 9 Fe(acac)₃ Pb 5 Cu 2 — TEAC 2

[0040] The results show that various combinations of Fe, IOCC, oniumhalide, and base can effectively catalyze the carbonylation reaction.

Example 6

[0041] The general procedure of Examples 1-5 was repeated with an ironsource selected from either acetylferrocene (“CH₃COC₅H₄FeC₅H₅”) ortris(2,2,6,6-tetramethyl-3,5-heptanedionate) iron (III) (“Fe(TMHD)₃”).The remainder of the catalyst system included TEAB, and either Cu(acac)₂or PbO. Reactions were carried out at approximately 107 atm. in a 7.79%oxygen in CO atmosphere to produce the following results: Experi-Cu(acac)₂ PbO ment Equiva- Equiva- TEAB Fe No. Iron source lents lentsEquiv. TON 1 CH₃COC₅H₄FeC₅H₅ 5 — 75 2 2 CH₃COC₅H₄FeC₅H₅ — 5 75 3 3Fe(TMHD)₃ — 5 75 3 4 Fe(TMHD)₃ — 5 75 4

[0042] The results show that various combinations of Fe, IOCC, and oniumbromide can effectively catalyze the carbonylation reaction.

[0043] It will be understood that each of the elements described above,or two or more together, may also find utility in applications differingfrom the types described herein. While the invention has beenillustrated and described as embodied in a method and catalyst systemfor producing aromatic carbonates, it is not intended to be limited tothe details shown, since various modifications and substitutions can bemade without departing in any way from the spirit of the presentinvention. For example, additional effective IOCC compounds can be addedto the reaction. As such, further modifications and equivalents of theinvention herein disclosed may occur to persons skilled in the art usingno more than routine experimentation, and all such modifications andequivalents are believed to be within the spirit and scope of theinvention as defined by the following claims.

What is claimed is:
 1. A method of carbonylating an aromatic hydroxycompound, said method comprising the step of contacting at least onearomatic hydroxy compound with oxygen and carbon monoxide in thepresence of a carbonylation catalyst system comprising an effectiveamount of an iron source in the absence of an effective amount of aGroup VIII B metal source.
 2. The method of claim 1 , wherein thecarbonylation catalyst system further comprises a catalytic amount of aninorganic co-catalyst.
 3. The method of claim 2 , wherein the inorganicco-catalyst is a copper source.
 4. The method of claim 2 , wherein theinorganic co-catalyst is a lead source.
 5. The method of claim 1 ,wherein the carbonylation catalyst system further comprises acombination of inorganic co-catalysts.
 6. The method of claim 5 ,wherein the combination of inorganic co-catalysts comprises a catalyticamount of a copper source and a catalytic amount of a zirconium source.7. The method of claim 5 , wherein the combination of inorganicco-catalysts comprises a catalytic amount of a titanium source and acatalytic amount, of a cerium source.
 8. The method of claim 5 , whereinthe combination of inorganic co-catalysts comprises a catalytic amountof a lead source and a catalytic amount of a titanium source.
 9. Themethod of claim 5 , wherein the combination of inorganic co-catalystscomprises a catalytic amount of a lead source and a catalytic amount ofa zirconium source.
 10. The method of claim 5 , wherein the combinationof inorganic co-catalysts comprises a catalytic amount of a coppersource and a catalytic amount of a titanium source.
 11. The method ofclaim 5 , wherein the combination of inorganic co-catalysts comprises acatalytic amount of a copper source and a catalytic amount of a leadsource.
 12. The method of claim 5 , wherein the combination of inorganicco-catalysts comprises a catalytic amount of a titanium source and acatalytic amount of a zirconium source.
 13. The method of claim 1 ,wherein the carbonylation catalyst system further comprises an effectiveamount of a halide composition.
 14. The method of claim 13 , wherein thehalide composition is an onium bromide composition.
 15. The method ofclaim 13 , wherein the halide composition is an onium chloridecomposition.
 16. The method of claim 1 , wherein the aromatic hydroxycompound is phenol.
 17. The method of claim 2 , wherein thecarbonylation catalyst system further comprises an effective amount of abase.
 18. A method of carbonylating an aromatic hydroxy compound, saidmethod comprising the step of: contacting at least one aromatic hydroxycompound with oxygen and carbon monoxide in the presence of acarbonylation catalyst system comprising the following components: aneffective amount of an iron source in the absence of an effective amountof a Group VIII B metal source; a catalytic amount of an inorganicco-catalyst; and an effective amount of a halide composition.
 19. Acarbonylation catalyst system, comprising an effective amount of an ironsource in the absence of an effective amount of a Group VIII B metalsource.
 20. The carbonylation catalyst system of claim 19 , furthercomprising a catalytic amount of an inorganic co-catalyst.
 21. Thecarbonylation catalyst system of claim 20 , wherein the inorganicco-catalyst is a copper source.
 22. The carbonylation catalyst system ofclaim 20 , wherein the inorganic co-catalyst is a lead source.
 23. Thecarbonylation catalyst system of claim 19 , further comprising acombination of inorganic co-catalysts.
 24. The carbonylation catalystsystem of claim 23 , wherein the combination of inorganic co-catalystscomprises a catalytic amount of a copper source and a catalytic amountof a zirconium source.
 25. The carbonylation catalyst system of claim 23, wherein the combination of inorganic co-catalysts comprises acatalytic amount of a titanium source and a catalytic amount of a ceriumsource.
 26. The carbonylation catalyst system of claim 23 , wherein thecombination of inorganic co-catalysts comprises a catalytic amount of alead source and a catalytic amount of a titanium source.
 27. Thecarbonylation catalyst system of claim 23 , wherein the combination ofinorganic co-catalysts comprises a catalytic amount of a lead source anda catalytic amount of a zirconium source.
 28. The carbonylation catalystsystem of claim 23 , wherein the combination of inorganic co-catalystscomprises a catalytic amount of a copper source and a catalytic amountof a titanium source.
 29. The carbonylation catalyst system of claim 23, wherein the combination of inorganic co-catalysts comprises acatalytic amount of a copper source and a catalytic amount of a leadsource.
 30. The carbonylation catalyst system of claim 23 , wherein thecombination of inorganic co-catalysts comprises a catalytic amount of atitanium source and a catalytic amount of a zirconium source.
 31. Thecarbonylation catalyst system of claim 19 , further comprising aneffective amount of a halide composition.
 32. The carbonylation catalystsystem of claim 31 , wherein the halide composition is an onium bromidecomposition.
 33. The carbonylation catalyst system of claim 31 , whereinthe halide composition is an onium chloride composition.
 34. Thecarbonylation catalyst system of claim 20 , wherein the carbonylationcatalyst system further comprises an effective amount of a base.
 35. Acarbonylation catalyst system, comprising an effective amount of an ironsource in the absence of an effective amount of a Group VIII B metalsource; a catalytic amount of an inorganic co-catalyst; and an effectiveamount of a halide composition.